1. Field of the Invention
The present invention relates to a liquid ejection head for ejecting liquid.
2. Description of the Related Art
An exemplary liquid ejection head is one used in an ink-jet printing method. In the ink-jet printing method, liquid droplets are ejected from ejection ports onto a recording medium, such as a sheet of paper, thereby printing images and characters.
An outer surface of an ink-jet print head on which ejection ports are open (hereinafter referred to as an “ejection surface”) is subjected to liquid-repellent treatment to facilitate the removal of deposited ink, for example, with a wiper. A liquid-repellent material must therefore be resistant to ink and wiping with a rubber blade.
U.S. Patent Application Publication No. 2007/0085877 discloses an ink-jet print head having an ejection surface treated with a particular liquid-repellent compound. The liquid-repellent compound has a siloxane skeleton having a liquid-repellent perfluoroalkyl group.
The ink-jet printing method has recently been used in various fields. Accordingly, various inks have been used in various ways. A certain ink-jet print head has a heating function to improve ejection characteristics. In some cases, an ink-jet print head is not used for many hours or days. Some conditions of use accelerate the evaporation of ink solvent in the vicinity of ejection ports on an ejection surface of an ink-jet print head. This may result in an increase in the viscosity of deposited ink and the solidification of deposited ink on the ejection surface, causing deterioration in ink ejection performance. Even with an ink-jet print head having a liquid-repellent ejection surface to improve printing characteristics, the evaporation of ink solvent can lower liquid repellency. Deposited ink may distort ejected droplets, resulting in undesirable print images and characters.